The present invention relates to door locks, and more particularly, to a door lock by which a doorknob can be selectively decoupled in operation from the door lock and become idle when the door lock is fastened, so as to prevent the door lock from being damaged in case of the doorknob being exerted with external impact or forcibly turned by a strong force.
As shown in FIG. 1, a conventional door lock mainly comprises: a housing 10xe2x80x2; a dead bolt 201xe2x80x2 received in the housing 10xe2x80x2 and operatably driven by a key (not shown); a latch bolt 401xe2x80x2 retained in the housing 10xe2x80x2 and operatably driven by at least a doorknob (not shown); a safety bolt 301xe2x80x2 urged to hold the latch bolt 401xe2x80x2 at a predetermined position; and a doorknob mechanism 50xe2x80x2 associated with the latch bolt 401xe2x80x2 and the doorknob, so as to transfer a force generated by turning the doorknob for driving the latch bolt 401xe2x80x2 to operate. In practical use, this conventional door lock mounted on a door allows a user to operate the doorknob and the latch bolt 401xe2x80x2 to open or close the door. When the door is locked by the door lock, the dead bolt 201xe2x80x2 and the latch bolt 401xe2x80x2 respectively protrude outwardly from the housing 10xe2x80x2 to be engaged with a lock coupler, which is installed at a frame of the door and corresponds in position to the door lock. In the meantime, the safety bolt 301xe2x80x2 is compressed by the frame of the door, and cooperates with a latch board 302xe2x80x2 to hold the latch bolt 401xe2x80x2 at the protruding position by which the door lock is fastened and the latch bolt 401xe2x80x2 is blocked against operation driven by the doorknob. Therefore, with the door lock being fastened, the door can be securely locked without being easily opened.
However, the above conventional door lock is inherent with significant drawbacks. When the door lock is fastened, since the latch bolt 401xe2x80x2 and the doorknob are operationally blocked, if the doorknob is exerted with external impact and forcibly turned by a strong force, the doorknob mechanism 50xe2x80x2 and other associated internal components would be easily damaged to impair the door lock. Moreover, the door lock is not provided with a fireproof mechanism for preventing the door from being opened when a fire occurs, and thereby is not applicable to a fire door. This is because, during the fire, if a fire door used for limiting spread of the fire is accidentally opened, fresh air is introduced and helps proliferate the fire, making damage caused by the fire even more severe.
Therefore, it is greatly desired to develop a door lock, which can be prevented from being damaged by externally-applied force or impact, and also suitably used for a fire door.
An objective of the present invention is to provide a door lock by which an outside knob can be selectively decoupled in operation from the door lock and become idle when the door lock is fastened, so as to prevent the door lock from being damaged in case of the outside knob being exerted with external impact or forcibly turned by a strong force.
Another objective of the present invention is to provide a door lock, whereby when a fire occurs, the door lock is urged by high temperature of the fire to hold a latch bolt at a position for fastening the door lock, so that a door mounted with the door lock is prevented from being opened during the fire, and spreading of the fire can be confined so as to minimize fire-induced damage.
In accordance with the above and other objectives, the present invention proposes a door lock, comprising: a housing integrally connected with a cover, for receiving internal components of the door lock therein; and a first and a second doorknobs externally connected to the internal components of the door lock.
The internal components of the door lock comprise: a dead bolt adapted to be operatably driven by a key through a keyhole formed on the housing; a latch bolt adapted to be operatably driven by at least one of the first and second doorknobs; a first doorknob mechanism associated with the latch bolt and the first doorknob; and a second doorknob mechanism integrally connected to the first doorknob mechanism, and associated with the latch bolt and the second doorknob.
In particular, the first doorknob mechanism comprises: a first body formed with a recessed portion; a first pivot member received in the recessed portion of the first body, and externally connected to the first doorknob, so as to allow the first doorknob to be operationally associated with the first pivot member; at least a first coupling member adapted to be capable of being selectively coupled to the first body and the first pivot member; a first fixture attached onto the first body and associated with the latch bolt, the first fixture being adapted for retaining the first pivot member within the recessed portion of the first body, and for preventing the first coupling member from escaping out of the first body; and a control means associated with the first coupling member, for manually controlling positioning of the first coupling member with respect to the first body and the first pivot member.
The second doorknob mechanism is connected to the first doorknob mechanism, and comprises: a second body formed with a recessed portion, and engaged with the first body of the first doorknob mechanism in a manner that, the recessed portion of the second body is positionally opposed to the recessed portion of the first body; a second pivot member received in the recessed portion of the second body, and externally connected to the second doorknob, so as to allow the second doorknob to be operationally associated with the second pivot member; at least a second coupling member adapted to be simultaneously coupled to the second body and the second pivot member; a second fixture attached onto the second body and associated with the latch bolt, the second fixture being adapted for retaining the second pivot member within the recessed portion of the second body, and for holding the second coupling member in position; and at least a fixing means for integrally connecting the second fixture, the second coupling member and the second body, so as to allow the second pivot member and the second doorknob to cooperate with the second doorknob mechanism as a whole for driving the latch bolt to operate.
In another embodiment, the control means can be associated with the first coupling member by a power means, which provides power for driving operational association between the control means and the first coupling member.
With the use of the above door lock, the first doorknob usually assembled at the outside of a door (i.e. outside knob), can be manually controlled to be operationally associated with or dissociated from the first doorknob mechanism of the door lock. In other words, when the door lock is fastened, the outside knob can be selectively decoupled from the door lock and become idle; this is greatly beneficial as to prevent the door lock from being damaged even if the outside knob is exerted with external impact or forcibly turned by a strong force.
The internal components of the above door lock further comprise: a fireproof mechanism having a blocking member associated with the latch bolt, and a positioning means for allowing the blocking member to be interposed between the latch bolt and the positioning means, the positioning means being formed with a movable portion and a fixed portion, wherein the blocking member is shifted from a first position in contact with the movable portion of the positioning means, to a second position in contact with the fixed portion of the positioning means in response to high temperature. When the blocking member is held at the first position, the latch bolt is operatably driven by the doorknob to freely open the door equipped with the door lock. Alternatively, when a fire occurs and the blocking member is shifted to the second position in response to high temperature of the fire, the latch bolt would be kept in a position for fastening the door lock and operationally blocked by the fixed portion of the positioning means; this prevents the door from being opened during the fire, thereby confining spreading of the fire to minimize fire-induced damage.